Telephone system.



Patented Dec. 17, 1918.

INVENTOR.

FRANK M. SLOUGI'I J0 [Q HIS A TTOR fililgSSES FRANK M. SLOUGH, OF ROCHESTER, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS,

'IO STROMBERG-CARLSON TELEPHONE MFG. 00., OF ROCHESTER, NEW YORK, A GOR- Specification of Letters Patent.

TELEPHONE SYSTEM.

Patented Dec. 17,1918.

Application filed October 18, 1913, Serial No. 795,924. Renewed March 9, 1918. SerialNo. 221,576.

To all whom it may concern:

Be it known that I, Fnaxn M. SLoUoH, a citizen'of the United States, residing at Rochester, in the county of Monroe and State of- New York, have invented certain new and useful Improvements in Telephone Systems; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it, appertains to make and usethe same.

My invention relates to telephone systems, in which telephone lines lead to a main or central station where they are connected together by some suitable means.

The object of my invention is to improve the telephone systems at present in use, so asto shorten the time and lessen the trouble of operation. I aim to do this with the use of as little apparatus as possible and to so arrange the-same that a marginal operation is practically eliminated.

The specific objects of my invention, as well as the other general objects and uses thereof will probably be better understood from a description of particular apparatus embodied in the invention.

The figure illustrates diagrammatically a telephone system embodying my invention.

Referring now to the embodiment of the invention illustrated in the drawing, at A I show a 'subscribers line leading from a substation B t a main or central station C. For the sake of convenience, I will designate the line A the calling line or'line of the calling party, becauseinthe description of the operation of the system .I will assume that the subscriber at B is the calling subscriber.

The subscriber at B is provided with substation talking a'pparatus. including a re ceiver 15, a transmitter 16 and a signaling apparatus, such HS a hell 17. This line extends by conductors lSand 19 to the main.

station C, Where it terminates in an element of a switching mechanism. such as a jack 20, here shown as consisting of a thimble contact 21, a tip, contact spring 22 and a sleeve contact spring 23. Line signaling apparatus 24 may be employed. here consisting of a lamp 25 and a-line relav 26. A cut-ofi relay 27 may be employed for severing the connection between theapparatus 24 and the line A.

At the main station I provide means for connecting the lines together. This apparatus is adapted to be connected to the line by the switching mechanism, to which I have previously referred. In the embodiment illustrated the connecting apparatus consists of a cord circuit D, here shown as terminating in an element of the above mentioned switching mechanism, and such element here consists of a plug E at one end and a plug F at the other. The plug E inpart of the operation and to exclude her during another part. The plug F is provided with elements adapted to register with the elements of the jack 31 of the called line H. The apparatus used in connection with the called line is so similar to that used in connection with the calling line, that it will be useless to describe it here, except that it is shown as a party line; that a signal device, such as a bell, is employed at each station; that the line extends by conductors 33 and 34 from subscribers stations to the main station; and that line signal apparatus 35 and a cut-ofi relay 36 are employed in connection therewith.

Suitable means is provided for supply ng energy to operate the signal devices illustrated at 17 and 32. In the form sho n this consists-of generators 37 38, 39 and '10. Any-of these generators are adapted to be connected in circuit with the signal ng devices on the called line and I provide conductors and suitable means controlling said conductors for performing such function.-

In the form shown this is done by depressing one of the series of ringing keys I- which causes the connection of such source to the called line. Means are provided for continuing at intervals the appli ation of energyfor the actuation of the signal at the subscribers station until the subscriber responds, whereupon it is automaticallydisconnected I also provide means for automatically disconnecting the plugs E and F from the cord circuit after the subscribers have retired their subStatiOn'apParatusJ A signal is also provided which is operated towarn a desired party that the conversation is completed and that the connections are to be restored to normal;

. The objects of my invention and the particular embodiment will probably be better understood from a description of the operation of the system, which is as follows Assuming that the subscriber at B desires to communicate with the subscriber at J upon the called line, the receiver 15 is re- 'moved from the receiver hook40, which is spring pressed upward and automatically pleting a circuit fromground 349through 27 21 30 T 350 5152 relay 1-bat tery53ground 54actuating the cut-off relay which attracts its armatures 44 and 47, disconnecting the line signaling apparatus of the called line from the conductors 18 and 19. v The relay 1 is energized, attract ing its armatures 55 and 56, closing switches 55-57 and 56-58, and connecting the operators set G to the cord circuit and in circuit with the subscribers apparatus at 3 over the following circuit: G5960-6157 5562-'63+6429 231-8151641 69--7071 back to G. Current will be supplied to' this circuit from the battery 72-, which courses through the relay 3 and the conductors 68 and 73 to the cord circuit and over the conductors just traced through the substation apparatus at B, energizing the relay 3, which attracts its armature 74, closing a switch 7475 for a purpose ,to be described. The operator then talks with the subscriber, learning that it is the station at J that is wanted. The plug F is inserted into the jack 31, completing a circuit through the relay 2 as follows: ground 80battery 8lrelay 2bonductor 83contacts 84 858687 to ground through the relay 36;

36 will be energized, attracting its armatures and severing the called line signaling apparatus from the called line. The relay 2 will be energized, attracting the armatures and 59, disconnecting the operators set from the cord circuit and making it impossible to listen in to the conversation which takes place between. the subscribers at B and J. The armature 88 will be attracted, closing a Assuming that this is the device 37, the key.

97 will be actuated, closing the switch 9798 and completing a circuit for the ma and 4 as follows: ground 10098-9 99 101 110 4 109 102103-- 10489- 8S90 and 91. The magnet 99 will be energized, attracting its armature 106, closing a switch 105-106 and locking the relay from ground 107 through conductor '108,

switch 106-405 and over the circuit just traced.

Also the magnet 4 will be energized, attracting its armatures lll, 112 and 113, interrupting the tip strand of the cord at 111114 and grounding the tip at 111115. The sleevestrand is interrupted at 112116 andconnected at 112,117 to a conductor 118'leading to a' contact 119 which is connected to a second contact 120 when the magnet 99 is energized. A second path is created for current through the switch 113121, the conductor 122 and one of the windings of the magnet 5 on to the sleeve side of the cord.

Thus, after the magnetization of the relays 4 and 99, which has been described, a circuit will be completed for the application of the energy of the source 37 to the signal 32 as follows: from ground 125-through 37, the interrupter 12 6-conductor 127contacts 120119conductor 118-and in parallel through 128-117112to the sleeve and 1211131221nagnet 5 and conductor 129 to the sleeve,-from the sleeve to the side 34 of line, through the signal device 32 back over the side 33 of line to the tip 130, through contacts 131132-111 115to ground at 133. The ringing continues at intervals, whose length is determined by the character of the segment upon the interrupter 126 and the rate of its rotation.

Owing to the resistance of thebell bridgeat the substation, the current through this circuit will not be sufiicient to actuate the relay 5. hen the called subscriber at J responds, the substation talking set is placed in bridge of the line and this being of lower resistance than the bell bridge, the energy through the circuit just described has increased, sothat the relay '5 will now be actuated. The magnet 5 attracts its armature 103, opening the switch 102103 in the circuits ofthe relays 4 and 99, which are deenergiz ed, restoring their armatures and the apparatus controlled thereby to the position ets 99 shown in the drawing, disconnecting the ringing current from the line, renewing the continuity of the cord circuit and connecting the magnet 5 through a switch 113-14-.0 to a source 141 and over a circuit just traced in connection with the I, ringing circuit through the subscribers li'treand the magnet 5, keeping thesame energized and placing it under control of the subscribers set, so that it remains actuated as long as the subscriber is on the line.

The relay 5 also attracted an armature 14% and closed a switch lH-Hf), completing a second shunt 146 about the magnet 8 for a purpose to be described.

The apparatus is now in condition for conversation and the same takes place, its length being determined by the desire of the subscribers. At the end oi? the conversation, the receivers are restored to the hooks, interrupting the line circuits and the circuits of the relays 3 and 5, which release their armatures T4: and 1H, interrupting the shunts about the relay 8 which will become energized over the circuit previously traced. \Vhen this relay is energized, it attracts the armatures 65, 6t and 51, interrupting the circuits of the relays 27 and 1, and restoring the switches et6--4:7 and -l445 to the condition illustrated in the drawing. The attraction of the armatures 64: and 65 automatically disconnects the switching mechanism shown at E20 from the connecting apparatus D and releases the line A from the connection so that the line-can be used for other calls immediately upon the termination of the conversation.

\Vhen the armature 65 was attracted, 'a'

switch 65-150 was closed, completing a circuit through the magnet 10 as follows: 48- -t7-.i-(i-22-"28-65150r10-bfibtelfy 157 to ground at 152. The relay magnet 101$ wound with a great many turns of very fine wire. so that it will be of very high resistance and on account of the great number of turns of wire, can be energized with a very small amount of current. This relay when -the foregoing circuit is completed, attracted the armature 153. completing a circuit for the magnet 9 as follows: ground 155-+batteryniagnet 9conduetor 156 1541,531nagnet 8 to ground at 9t and energizing the magnet 9. This magnet would likewise be shunted through the shunts controlled by the relays 3 and 5 when either of these relays is energized, so that in the form of my invention illustrated the magnet 9 is controlled by the subscribers apparatus. The magnet 9 when energized attracted the armatures 131 and 161. cutting off the plug I from the cord D and releasing the line Hi The armature 85 was also attracted when the magnet 9 was energized, interrupting the circuit of the cut-oif relay 36 and the relay 2, the magnets 8 and 9 now being energized over the following circuit:

01 8 153 154 156 9 -battery to -follows: ground at 170battery-magnet 11.contact 171131130through the tip and contacts of the :relay 3(3to ground. The relay magnet 11 is wound with very tine wire in a manner similar to the magnet 10. The magnet 11 is energized, attracting its armature 17 t and closing a circuit 1741T5 through battery and a disconnect signal 176 which becomes energized, indicating to the operator that the conversation is terminated. This signal continues to burn until such time as the operator finds it convenient to withdraw the plugs E and F, disconnecting the cord from the line This withdrawal interrupts the circuits of the magnets 10 and 11, which in turn interrupt the circuits of the magnets 8 and 9 and the signal 12, restoring the apparatus to the normal condition illustrated in the drawing.

I claim:

1; In a telephone system, the combination of a main station, a plurality of substations, switches at the substations, telephone lines connecting the substations to the main station, connecting apparatus at the main station for connecting telephone lines together, switching mechanism for connecting the connecting apparatusto the telephone lines, an operator's telephone set at the main station adapted to be connected to the connecting apparatus, electromagnetic means for operatin contact-s in the connection of the operator's set to the connecting apparatus and means controlled by said first named means for automatically disconnecting the switching mechanism from the connecting apparatus.

In a telephone system, the combination of a main station, a plurality of substations, switches at the substations, telephone lines connecting the substations to the main station, connecting apparatus at the main station for connecting telephone lines together, switching mechanism for connecting the connecting apparatus to the telephone lines,

,an operators telephone set at the main station, means for connecting said set to such connecting apparatus, a relay operating contacts in said connecting means, and electromagnetic means-controlled by said relay tor automatically disconnecting the switching mechanism from the connecting apparatus.

3. In a telephone system, the combination of a main station. a calling telephone line. substation apparatus on said line, a called telephone line. substation apparatus on said line, a cord circuit at the main station for connecting said lines together, plug and ack Cir switching Inechanismfor connecting the cord circuit to the calling line and plug and jack switching apparatus for connecting the cord to the called line, an operators telephone'set, electromagnetic means for connecting the set to the cord, means controlling said connecting means and means operable by the. calling substation apparatus for cuit.

automatically disconnecting the calling line plug and jack switching mechanism from the cord, said last named means being controlled by the means which controls the conmotion of the operators set to the cord cir- 4. In a telephone system, the-combination of a main station, a calling telephone line, substation apparatus on said line; a called telephone line, substation apparatus on said line, a'cord circuit at the main station for connecting said lines together, plug and jack switching means for'iconnecting the cord circuit tothe calling line and plug and'jack switching apparatus for connecting the cord of a main station, a plurality of telephone lines including a calling line, substation apparatus on said calling line, a cord circuit at the main station for connecting telephone lines together, plug and jack switching .mechanism for connecting the cord to the calling line, an operators set adaptedto be connected to the cord circuit, a relay having contacts in the connections of the operators set to the cord circuit, electromagnetic means for automatically disconnecting said switching mechanism from the cord circuit, said electromagnetic means being controlled by said relay. v

6; -In a telephone system, the combination of amain station, a plurality of substations, Y

telephone lines connecting the substations to the-main station, a cord circuit for connectingtelephone lines together, an operators set at the main station, conductors for connecting the set to the cord circuit, normally open switches in said conductors, a magnet for closing said switches when the cord circuit is connected to a calling line and a mag net for opening said conductors, said last named magnet being operated by the act of connecting the cord to a called line, said last named magnet controlling said first named magnet.

7. In a telephone system, the combination of a main station, a called telephone line, a calling telephone line, substation apparatus on each line, a cord circuit at the main station, an answering plug for said cord-circuit and a calling plug for said cord circuit, said plugs adapted to connect the cord to the jacks of said lines, said cord including talking strands, means for automatically disconnecting the answering plug from the cord circuit and interrupting the strands of the cord circuit, said means including a relay under the control of the calling subscriber lines leading to the main station, substation apparatus on the subscribers lines, connecting apparatus at the main station for connecting telephone lines together, switching mechanism for connecting said apparatus to the telephone lines, means associated'with said connecting. apparatus controlled by substation a paratus, means for disconnecting the switch ing apparatus, a source of energy for sup plying energy to said disconnecting means, said disconnecting means being included with the source of-energy in a circuit local to said connecting apparatus and means gov-- ernedby said subscriber controlled means for shunting the energy of said source from said disconnecting means.

' 9. In a telephone system, the combination of a main station, a plurality of subscribers lines leading to the main station, substation apparatus on said lines, connecting apparatus at the main station for connecting telephone lines together, switching mechanism for connecting said apparatus to thetelephone lines, a device associated with said connecting apparatus controlledby substation apparatus, electromagnetic means for disconnecting the switching mechanism from the connecting apparatus, a circuit for-said electromagnetic means local to said connecting apparatus and a shunt for said electro: magnetic means governed by said subscriber controlled device. v

10. In a telephone system, the combination'of a main station, a calling telephone line leading to said main station, substation apparatus on said calling line, 2 called Iine leading to the main station, substation apparatus on the called line, acord circuit for connecting said lines together, plug and jack switching mechanism for connecting the cord to the lines, a relay for disconnecting the cord from the plug and jack switching 'mechanism of the calling line, a second relay for disconnecting the plug and jack switching mechanism of the called line from the cord, circuits for said relays, shunts ing mechanism from the connectabout said relays and means governed by said substation apparatus controlling said shunts.

11. In a telephone system, the combination of a main station, a plurality of telephone "lines, including a called line, leading to the main station, substation apparatus on said lines, a cord circuit at the main station, plug and jack switching mechanism for connecting the cord to the lines, means for disconnecting said plug and jack switching mechanism from the cord, electromag netic means for actuating the same, a circuit for said electromagnetic means local to said cord circuit, and a shunt about said electromagnetic means controlled by the substation apparatus of a subscriber on the called line.

12. In atelephone system, the combination of a main station, a plurality of substations, telephone lines leading from the substations to the main station, a cord circuit at the main station for connecting telephone lines together, switching mechanism at each end of the cord for connecting the cord to a telephone line, means for disconnecting the switching mechanism at one end of the cord from'the cord and means for disconnecting the switching mechanism at the other end from the cord, one of said means controlling the other.

13. In a telephone system, the combination of a main station, a calling subscribers line leading to said main station, a called subscribers'line leading to said main station,

" a cord circuit for connecting said lines together, a switching device for connecting the cord to the calling line, a second switching device forconnecting the cord to the called line, means for disconnecting the cord from said second switching device and means controlling said first named means for disconnecting the cord from the first named switching device. j

14. In a telephone system, the combination of a mainstation, a plurality of telephone lines leading to the main station, substation apparatus on said telephone lines, a cord circuit at the main station, switching mechanism provided with contacting terminals for connecting the.cord circuit to the,

telephone lines, apparatus for disconnecting the switching mechanism from the cord circuit, a disconnect signal associated with the cord controlled by said apparatus, and a circuit for maintaining the disconnect signal, including contacting terminals of the switching mechanism.

15. In a telephone system, the combination of a main station, aplurality of telephone lines leading to the main station, substation apparatus at the main station, a cord circuit for connecting the lines together, a switching device provided with contacting terminals for connecting one end of the cord to ciated with the cord controlled by said electromagnetic apparatus, and a circuit for maintaining the disconnect signal, including contacting terminals of the switching device.

16. In a telephone system, the combination of a main station, a calling subscribers line leading to the main station, a cut-ofi' relay for said calling line, a cord circuit, a switching device for connecting the cord to the calling telephone line, a called tele phone line leading to the main station, a switching device for connecting the cord to the called line, means for automatically disconnecting the cord from said second named switching device, a circuit for said means, a relay controlling said circuit and a circuit for said relay controlled by the cut-off relay in the calling subscribers line.

17. In a telephone system, the combination of a main station, telephone lines leading to the main station, substation apparatus on the telephone lines, cut ofli relays for said lines, a-cord circuit, switching mechanism for connectingthe cord to telephone lines, means for disconnecting the cord from the switching apparatus, a relay controlling said means and a circuitfor said relay controlled by the cut-off relay of one of the subscribers lines.

18. In a telephone system, the combina-' tion of a main station, a called telephone line leading to the main station, a cord circuit, a switching device provided with contacting terminals for connecting the cord to the telephone line, a disconnect signal asso- 'ciated with the cord circuit, means controlling said disconnect signal for automatically disconnecting the switching device from the cord circuit, and a circuit for maintaining said disconnect signal, including contacting terminals of said switching device.

19. In a telephone system, the combination of a main station, a plurality of substations, telephone lines leading from the substations to the main station, a cord circuit for connecting the lines together, switching mechanism for conecting the cord to the lines, means for automatically disconnecting the cord from the switching mechanism, an operators telephone set, elec= tromagnetic means toconnect the telephone set to the cord and means controlling the operators connecting means controlled by said disconnecting means."

- 20. In a telephone system, the combina-v to such jacks, a source of current associated with the cord circuit, means including a relay, thev magnetof which is in a circuit local to the i-nain'station controlled by sub-.

station apparatus -for automatically disconnecting theanswering end of the plug from the cord circuit, and mechanism for retiring tion of a main station, a plurality of subscribers linesleading to the main station,

substation apparatus on said lines, connect- .ing apparatus at the main station for connecting telephone lines together, switching mechanism for connecting said apparatus to the telephone lines, a device associated with said connecting apparatus controlled by substation apparatus, electromagnetic means for automatically disconnecting the switching mechanism from the connecting apparatus-when a connected subscriber retires his substation apparatus, a circuit for said electromagnetic means, said circuit being local to said connecting apparatus and a shunt for said electromagnetic means governed by said subscriber controlled device.

22. In a telephone system,,the combination of a main station, a plurality of tele-' .phone lines, including a called line, leading to the main station, substation apparatus on saidlines, a cord circuit at the main station, plug and jack switching mechanism for connecting the cord to the line, means -for disconnecting said plug and jack switching mechanism from the cord, electromagnetic means in a circuit local to said'cord circuit for automatically actuating the same when connected substation apparatus is retired and a shunt about said electromagnetic means controlled by the substation apparatus ofa subscriber on the called line.

23. In a telephone system, the combination of a main station, a plurality of substation's, telephone lines leading from the substations to the main station, a cord circuit at the main station for. connecting telephone lines together, switching mechanism at each end of the cord for connecting the cord to a telephone line, means for automatically disconnecting the switching mechanism at one end of. the cord from the cord and means for automatically disconnecting the switching mechanism at the other end from the cord, one of said means controlling the other and each of said means being au to matically actuated when connected subscribers substation apparatus is retired 24. In a telephone system, the combination of a main station, a calling subscribers line leading -to said main station, a called a cord circuit for connecting said lines together, a switching device for connecting the cord to the calling line, a second switching device for connecting the cord to the called line, means 'for automatically disconnecting the cord from said second switching device when the called substation apparatus is. retired and means controlling said first named means for automatically disconnecting the cord from the first named switching device when the calling substation apparatus is retired.

25. In ,a telephone system, the combination of a main station, a plurality of telephone lines leading to the main station, substation apparatus on said telephone lines, a cord circuit at the main stat-ion, switching mechanism provided with contacting terminals for connecting the .cord circuit to the telephone lines, apparatus for automatically disconnecting the switching mechanism from the cord circuit when connected substation talking apparatus is retired, a disconnect signal associated with the cord controlled by said apparatus, and means for maintaining the disconnect signal, said means being included in circuit together with contacting terminals of said switching mechanism.

26. In a telephone system, the combination of a main station, a plurality of telephone lines leading to the main station, su'bstation apparatus at the main station, a cord circuit for connecting the lines togetherfia switching device for connecting one end of the cord to the telephone line, eletromagnetic apparatus for automatically disconnecting said switching device from the cord when connected subscribers talking apparatus is retired and a disconnect signal associated with the cord circuit controlled by said electromagnetic apparatus, said disconnect sig- -nal and, electromagnetic apparatus being maintained in an operative state over a circuit including a portion of a talking strand of said cord circuit and contacting terminals of said switching device. 27. In a telephone system, the combination of a main station, a calling subscribers line leading to the main station, a cut-off relay for said. calling line, 'a cord circuit, a switching device for connecting the cord to the calling telephone line, a called telephone line leading to the main station, a switching device for connecting the cord to the called,

line, means for automatically disconnecting the cord from saidsecond named switching device when connected subscribers talking apparatus is retired, a circuit for said means, a relay controlling said circuit and a circuit for said relav controlled by the cut-ofi rela in the calling subscribers line.

28. In a telephone system, the combination of a main station, telephone lines leading to the main station, substation apparatus 0n the telephonelines, cut-oft relays for said lines, a cord circuit, switching mechanism for connecting the cord to telephone lines, means for automatically disconnecting the cord from the switching apparatus when connected subscribers substation talking apparatus is retired, a relay controlling said means, and a circuit for said relav controlled py the cut-off relay of one of the subscribers mes.

29. In a telephone system, the combination of a main station, a called telephone line leading to the main station, a cord circuit, a switching device for connecting the cord to the telephone line, a disconnect signal associated with the cord circuit and means including a relay having its magnet in a circuit local to the main station, controlling said disconnect signal and for automatically disconnecting the switching device from the cord circuit when connected subscribers substation talking apparatus is retired, said relay being operatively main-- scribers talking apparatus is retired, an operators telephone set adapted to be connected to the cord andmeans controlling the connection of the operators set to the cord and controlled by said disconnecting means.

31. In a telephone system, the combination of a main station, a calling telephone line, substation apparatus on said line, a called telephone line, substation a paratus on said line, connecting apparatus at the main station for connecting the calling telephone line to the called telephone line, plug and jack switches for connecting said connecting apparatus to the telephone lines, two electromagnetic devices for disassociating the plug and jack switches from the connecting apparatus, one of which is under the control of the substation apparatus, the second being controlled by the firstelectromagnetic device.

32. In a telephone'system, the combination of a main station, telephone lines, substation apparatus on the telephone lines, switchboard jacks which the lines terminate, a cord circuit at the main station including talking strands, and an answering and a calling plug in which the cord terminates, means under the control of the calling subscriber for automatically disconnecting the answering plug from the cord circuit, said last named means including a relay and a circuit therefor, means to complete said circuit and maintain the 'disconnectipn of the answering plug from the cord c1rcu1t, said last named means including a relay and a circuit therestations for removing the control of the cut off relay oven the line signal of the calling line, thereby permitting the calling station .to regain control of the line signal of the calling line and means lncludlng a c1rcu1t for withholding the control of said line signal from said cut-ofi' relay.

34:. In a telephone system, the combination of telephone lines, each provided with a line circuit, telephone line interconnecting mechanisms for connecting telephone lines toether including talking strands adapted to be automatically interrupted at the termination of a conversation thereover, supervisory relay means associated with said mechanisms, a high resistance relay controlling the interruption of said talking strands, a circuit for said relay, including portions of one of said talking strands and a line circuit of a connected line, and means to close said circuit at the termination of a conversation and maintain suchcircuit closed until the connection is taken down.

35. In a telephone system, the combination of a telephone line provided with a subscribers set and a line circuit, telephone line interconnecting mechanism including a subscriber controlled relay and talklng strands adapted to be interrupted at the termination,

of a conversation over said strands, a high resistance relay controlling such interruption of such strands, a circuit for said relay including portions of a talking strand and such line circuit and means for closing said circuit upon the retirement of a subscriber and maintaining such circuit closed until the connection is taken down.

36. In a telephone system, the combination of telephone lines, each provided with a line.

of a connected line, means'to close said cir- 130 cuit at the termination of a conversation and maintain such circuit closed until the con-- nection is taken down, and a disconnect signal controlled by said high resistance relay,

37. In a telephone system, the combination of a telephone line provided with a subscribers set and a line circuit, telephone line interconnecting mechanism including'a subscri'ber controlled relay and talking strands adapted to be interrupted at the termination of a conversation over said strands, a high resistance relay controlling such lnterrupt1on of such strands, ,a circuit for said relay including portions of a talking strand. and

-cluding talking strands for connecting said lines together, a first connection switch for connecting said link conductors to a telephone line, a second connection switch for connecting said conductors to another telephone line, a disconnect relay adapted to cause the disconnection of said talking strands from a switch when the conversation is completed, a circuit for said relay including contacts of the first switch, and disconnect signal apparatus including a disconnect signal relay and a circuit therefor which in eludes contacts of the other switch.

39. In a telephone system, the combination of telephone line interconnecting means including talking strands adapted to be interrupted at the termination of a-conversation,

a relay controlling such interruption, a disconnect slgnal and a dlsconnect signal relay and circuits for said relays, each including a portion of a talking strand.

i In witness whereof, I have signed my name in the presence of two-Witnesses this 15th day of October, 1913.

' FRANK M. SLOUGH.

Vitnesses GEO. E. ROBERT, R. G. SANDS. 

